JP2004297549A - Radio equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radio equipment capable of sufficiently obtaining an attenuation quantity to the wraparound of a transmission signal and surely preventing the wraparound of the signal from a transmitting part to a receiving part. <P>SOLUTION: A first duplexer 21 and a second duplexer 22 are switched by high frequency switches 20, 27 and 28 and an antenna 17 is shared by the transmitting part 30 and the receiving part 40. The first duplexer 21 is constituted of a band-pass filter 23 for transmission and a band-pass filter 24 for reception, selects and passes signals with a frequency of a LOW band in a transmitting band and a receiving band. The second duplexer 22 is constituted of a band-pass filter 25 for transmission and a band-pass filter 26 for reception, selects and passes signals with a frequency of a HIGH band in the transmitting band and the receiving band. A modem 50 switches and controls the high frequency switches 20, 27 and 28 based on a channel setting signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an advanced cruise-assist highway system (AHS) in ITS (Intelligent Transport Systems) and a smart gateway system (SGW: Smart Gateway) for future Internet connection. The present invention relates to a wireless device for short-range communication (DSRC: Dedicated Short Range Communication) used for a roadside base station for a demonstration test.
[0002]
[Prior art]
2. Description of the Related Art In recent years, on toll roads, an ETC (Electronic Toll Collection System) has been adopted as a toll collection system. The radio equipment used for the ETC has a transmission speed of 1 Mbps, ASK (Amplitude Shift Keying) modulation (ARIB (Association of Radio Industries and Businesses: Radio Industry Association) STD T55 specification compliant), but is supported by the ITS in the road system. ARIB STD is a wireless device for short range communication (DSRC) used for a roadside base station for a demonstration test of a smart gateway system (SGW) or a smart gateway system (SGW).
The T75 standard (constructed from April 2002) is used.
[0003]
According to the ARIB STD T55 standard, the transmission channel is 2 channels for both transmission (downlink) and reception (uplink), the transmission band is 5790 to 5810 MHz for transmission, 5830 to 5850 MHz for reception, and the interval between the transmission band and the reception band is 20 MHz. Has become.
[0004]
In the ARIB STD T75 standard, the transmission channel is 7 channels for each of transmission (down) and reception (up), and the transmission band is 5772.5 to 5807.5 MHz for transmission, 5812.5 to 5847.5 MHz for reception, The interval between the transmission band and the reception band is 5 MHz.
[0005]
In the wireless device, one antenna is shared for transmission and reception using a duplexer (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-7-95112
[Problems to be solved by the invention]
When one antenna is used for both transmission and reception by the duplexer as described above, according to ARIB STD T55 standard, the transmission channel is two for each of transmission and reception, the transmission band is narrow, and the transmission band and the reception band are narrow. Is set as wide as 20 MHz, the characteristics of the duplexer can be easily adapted to the standard.
[0008]
However, in the ARIB STD T75 standard, transmission channels are used for transmission and reception, each having seven channels, the transmission band is wide, and the minimum interval between the transmission band and the reception band is set as narrow as 5 MHz. With a duplexer filter, it is very difficult to match the characteristics of the duplexer to a standard. If the filter characteristic of the duplexer is insufficient, a signal wraparound from the transmission unit to the reception unit occurs. However, if the minimum interval between the transmission band and the reception band is 5 MHz, it is not possible to sufficiently reduce the leakage of the transmission signal. .
[0009]
The present invention has been made in order to solve the above-described problems, and even when the minimum interval between the transmission band and the reception band is set to be small, it is possible to sufficiently obtain the amount of attenuation of the transmission signal wraparound, It is an object of the present invention to provide a wireless device capable of reliably preventing a signal from passing from a unit to a receiving unit.
[0010]
[Means for Solving the Problems]
The wireless device according to the present invention is a transmitting unit that transmits a high-frequency signal, a receiving unit that receives an external high-frequency signal, a plurality of duplexers having different bands that share an antenna with the transmitting unit and the receiving unit, And a changeover switch for switching a plurality of duplexers in accordance with the set channels of the transmission unit and the reception unit.
[0011]
As described above, the antenna is shared by a plurality of duplexers having different bands, and the duplexer is selected in accordance with the set channel, so that the filter characteristics of the duplexer can be adapted to the standard. Therefore, even when the minimum interval between the transmission band and the reception band is set to be narrow, it is possible to obtain a sufficient amount of attenuation with respect to the wraparound of the transmission signal, and to reliably prevent the wraparound of the signal from the transmission unit to the reception unit. And a stable operation can be performed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an overall schematic configuration of a narrow area communication system according to one embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a communication system control device, which is provided, for example, in a communication center or the like. The communication system controller 11 performs data control of the entire system, and includes a plurality of base stations 14 a to 14 a through an optical signal input / output device (optical I / O (input / output)) 12 and an optical fiber cable 13. 14n.
[0013]
Each of the base stations 14a to 14n includes an optical signal input / output device (optical I / O) 15, a base station radio 16, and an antenna 17, and has a predetermined interval, for example, several tens of meters along a communication area, for example, a highway. And wirelessly communicates with a vehicle-mounted device mounted on a traveling vehicle. Different transmission / reception channels are respectively allocated to the base stations 14a to 14n in advance.
[0014]
In the above-described configuration, the base stations 14a to 14n transmit, for example, TDMA (Time Division Multiple Access) type downlink data to a predetermined area of an expressway. When the traveling vehicle enters the communication area of the base stations 14a to 14n, for example, the communication area of the base station 14a, receives a radio wave from the base station 14a, and recognizes an empty slot, it transmits a line join request (ACTC: Activation Control Channel). I do. The base station 14a allocates an empty slot to the in-vehicle device of the traveling vehicle, and starts transmission and reception of data when the line connection with the in-vehicle device is completed. Data to be transmitted to the on-vehicle device is transmitted from the communication system control device 11 to the base station 14a via the optical fiber cable 13, ASK / QPSK modulated according to the T75 transmission procedure, and transmitted from the antenna 17 to the on-vehicle device of the traveling vehicle.
[0015]
On the other hand, transmission data from the in-vehicle device of the traveling vehicle is received by the base station 14a, collected by the communication system controller 11 by the optical fiber cable 13, and processed.
[0016]
As described above, the in-vehicle device of the traveling vehicle sequentially communicates with the base stations 14a to 14n in each communication area as the vehicle travels, and travels on the highway while receiving, for example, information on traffic congestion and accidents.
[0017]
Next, a detailed configuration of the base station radio 16 will be described with reference to FIG. The base station radio 16 includes a first duplexer 21, a second duplexer 22, high-frequency switches 20, 27, 28 for switching the duplexers 21, 22 as shown in FIG. 30, a receiving unit 40 for receiving a signal from a vehicle-mounted device, a modem unit 50 for modulating / demodulating a transmission / reception signal, and a wireless control unit 51.
[0018]
The antennas 17 provided in each of the base stations 14a to 14n are selectively connected to the first duplexer 21 and the second duplexer 22 via the high-frequency switch 20, respectively. In the high-frequency switch 20, the common terminal c is connected to the antenna 17, one switching terminal a is connected to the first duplexer 21, and the other switching terminal b is connected to the second duplexer 22.
[0019]
The first duplexer 21 includes a transmission band-pass filter (transmission BPF) 23 and a reception band-pass filter (reception BPF) 24, and selects a signal of a LOW band frequency in the transmission band and the reception band. And let it pass.
[0020]
The second duplexer 22 includes a transmission band-pass filter (transmission BPF) 25 and a reception band-pass filter (reception BPF) 26, and selects a signal of a HIGH band frequency in the transmission band and the reception band. Let through.
[0021]
As shown in FIG. 3, the first duplexer 21 covers the band (4 channels) of 5772.5 to 5792.5 MHz in the transmission band by the transmission bandpass filter 23 and receives by the reception bandpass filter 24. It is set to a type 1 LOW band that covers the band (4 channels) of 5812.5 to 5832.5 MHz in the band.
[0022]
Also, the second duplexer 22 covers the band (4 channels) of 5787.5 to 5807.5 MHz in the transmission band by the transmission band-pass filter 25, and 5727.5 to 5847 by the reception band-pass filter 26. It is set to a type 2 HIGH band covering a band of 0.5 MHz (4 channels).
[0023]
As described above, the first duplexer 21 and the second duplexer 22 cover four channels each in the transmission band and the reception band. However, since one channel is overlapped, a total of seven channels are covered. The transmission band and the reception band of the type 3 covered by the type 1 of the LOW band and the type 2 of the HIGH band are ARIB STD.
It matches the T75 standard.
[0024]
FIG. 4 shows a specific characteristic example (a type 2 HIGH band) of the reception band-pass filter 26 covering the band of 5827.5 to 5847.5 MHz in the reception band in the second duplexer 22. Things.
[0025]
In FIG. 2, the transmission bandpass filter 23 of the first duplexer 21 has a signal input terminal connected to the switching terminal a of the high frequency switch 27 and a signal output terminal connected to the switching terminal a of the high frequency switch 20. You. The reception band-pass filter 24 has a signal input terminal connected to the switching terminal a of the high-frequency switch 20 and a signal output terminal connected to the switching terminal a of the high-frequency switch 28.
[0026]
The transmission band-pass filter 25 of the second duplexer 22 has a signal input terminal connected to the switching terminal b of the high-frequency switch 27 and a signal output terminal connected to the switching terminal b of the high-frequency switch 20. The reception band-pass filter 26 has a signal input terminal connected to the switching terminal b of the high-frequency switch 20 and a signal output terminal connected to the switching terminal b of the high-frequency switch 28.
[0027]
The high-frequency switches 20, 27, and 28 are configured by, for example, semiconductor switches, and are switched by a switching command from the modem unit 50.
[0028]
The transmission signal from the transmission unit 30 is input to the switching terminal c of the high-frequency switch 27, and the reception signal extracted from the switching terminal c of the high-frequency switch 28 is input to the reception unit 40.
[0029]
The transmission section 30 includes an IF (intermediate frequency) amplifier 31, a mixer 32, a power amplifier 33, a local oscillator 34, and a PLL (Phase-Locked Loop) circuit 35. The transmission unit 30 amplifies the transmission IF signal transmitted from the modem unit 50 by the IF amplifier 31, and converts the transmission IF signal into a high frequency signal of a predetermined channel by a frequency conversion unit including a mixer 32, a local oscillator 34, and a PLL circuit 35. The signal is amplified by the power amplifier 33 and output to the switching terminal c of the high frequency switch 27.
[0030]
On the other hand, the receiving unit 40 includes a low noise amplifier (LNA: Low Noise Amplifier) 41, a mixer 42, an IF amplifier 43, a local oscillator 44, and a PLL circuit 45. The receiving unit 40 amplifies the received signal sent from the switching terminal of the high-frequency switch 28 by the low-noise amplifier 41, and converts the signal into an IF signal by a frequency conversion unit including a mixer 42, a local oscillator 44, and a PLL circuit 45. The signal is amplified by the IF amplifier 43 and output to the modem unit 50.
[0031]
The modem unit 50 operates according to a control command from the wireless control unit 51, and performs modulation of a transmission signal, demodulation of a reception signal, switching of the high-frequency switches 20, 27, 28, and the like.
[0032]
The wireless control unit 51 includes, for example, a CPU and an external interface. The external interface transmits and receives signals to and from the communication system controller 11 via the optical signal input / output device 15 and the optical fiber cable 13.
[0033]
In the base stations 14a to 14n configured as described above, for example, a transmission channel and a reception channel to be used are set depending on a set place. When setting the channel, a channel setting signal is sent from the communication system controller 11 to each of the base stations 14a to 14n via the optical fiber cable 13. The radio control units 51 of the base stations 14 a to 14 n output a control command to the modem unit 50 according to the channel setting signal sent from the communication system control device 11. The modem unit 50 controls the operations of the PLL circuit 35 of the transmitting unit 30 and the PLL circuit 45 of the receiving unit 40 in accordance with a control command from the wireless control unit 51, and sets a transmission channel and a reception channel.
[0034]
Further, the modem unit 50 controls switching of the high frequency switches 20, 27, and 28 based on the channel setting signal. That is, if the channel setting is the LOW band of the type 1, the modem unit 50 switches the switching terminal c of the high frequency switches 20, 27, 28 to the terminal a to switch the transmission bandpass filter 23 of the first duplexer 21. And if the channel setting is the type 2 HIGH band, the switching terminal c of the high-frequency switches 20, 27, 28 is switched to the terminal b to transmit the second duplexer 22 for transmission. The bandpass filter 25 and the reception bandpass filter 26 are selected.
[0035]
When the transmission data is transmitted from the communication system control device 11, the modem unit 50 performs ASK / QPSK modulation on the data according to the T75 transmission procedure, and outputs the data to the transmission unit 30 as an IF signal. Also, when the receiving unit 40 receives a transmission signal from the on-vehicle device, the modem unit 50 demodulates the IF signal sent from the receiving unit 40, and the wireless control unit 51, the optical signal input / output device 15, the optical fiber Transmission to the communication system control device 11 via the cable 13
[0036]
Further, the modem unit 50 performs AGC control on the receiving unit 40 according to the level of the received signal.
[0037]
As described above, the antenna 17 is shared by the transmission unit 30 and the reception unit 40 by the plurality of duplexers 21 and 22 having different bands, and the duplexers 21 and 22 are selected according to the set channel. The filter 22 does not need to cover the entire band, but only needs to cover a specific band. Therefore, the filter characteristic can be a characteristic conforming to the standard, and transmission and reception can be performed over the entire band. Therefore, even when the minimum interval between the transmission band and the reception band is set to be narrow, it is possible to obtain a sufficient amount of attenuation with respect to the wraparound of the transmission signal, and to reliably prevent the wraparound of the signal from the transmission unit to the reception unit. And a stable operation can be performed.
[0038]
In the above embodiment, the high-frequency switches 20, 27, and 28 are automatically switched by a switching signal from the modem unit 50. Alternatively, for example, a channel switch is provided on the display panel, and the high-frequency switches 20, 27, and 27 are manually operated. , 28 may be switched.
[0039]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments.
[0040]
【The invention's effect】
As described in detail above, according to the present invention, the transmitting unit and the receiving unit share an antenna with a plurality of duplexers having different bands and select the duplexer according to the set channel. The filter characteristics can be made to conform to the standard, and transmission and reception can be performed over the entire band. Therefore, even when the minimum interval between the transmission band and the reception band is set to be narrow, it is possible to obtain a sufficient amount of attenuation against the transmission signal wraparound, and to reliably prevent the signal wraparound from the transmission unit to the reception unit. And a stable operation can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall schematic configuration of a short-range communication system according to an embodiment of the present invention.
FIG. 2 is an exemplary block diagram showing a detailed configuration of a base station radio according to the embodiment;
FIG. 3 is a view showing filter characteristics of a first duplexer and a second duplexer in the embodiment.
FIG. 4 is a view showing a specific characteristic example of a reception bandpass filter (type 2 HIGH band) constituting the second duplexer in the embodiment.
[Explanation of symbols]
11 communication system controller 12 optical signal input / output device (optical I / O)
13 optical fiber cables 14a to 14n base station 15 optical signal input / output device (optical I / O)
16 Base station radio 17 Antennas 20, 27, 28 High frequency switches 21, 22 Duplexers 23, 25 Bandpass filter for transmission (BPF for transmission)
24, 26 ... bandpass filter for reception (BPF for reception)
Reference Signs List 30 transmitter 31 IF amplifier 32 mixer 33 power amplifier 34 local oscillator 35 PLL circuit 40 receiver 41 low noise amplifier (LNA)
42 mixer 43 IF amplifier 44 local oscillator 45 PLL circuit 50 modem 51 wireless controller

Claims (4)

A transmitting unit that transmits a high-frequency signal, a receiving unit that receives an external high-frequency signal, a plurality of duplexers having different bands that share an antenna with the transmitting unit and the receiving unit, and the transmitting unit including the plurality of duplexers. And a changeover switch for changing over according to a setting channel of a receiving unit. 2. The wireless device according to claim 1, further comprising switch switching means for automatically switching the changeover switch according to a channel set by the transmission unit and the reception unit. The wireless device according to claim 1, wherein the duplexer includes a first duplexer that selects a low band within a set band and a second duplexer that selects a high band within a set band. The first duplexer includes a transmission band-pass filter for selecting a low band in a transmission band and a reception band-pass filter for selecting a low band in a reception band. 4. The radio apparatus according to claim 3, further comprising: a transmission band-pass filter for selecting a high band of the transmission band; and a reception band-pass filter for selecting a high band within the reception band.

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